Latest GRM Issue CMC Story - Upper PHR Brace Modification Query

[NickV]

Was reading the CMC2 car writeup in the latest GRM issue, and something caught my eye in one of the pics (see attached). My question is regarding the gussets welded in to the upper brace above the panhard rod.

7.33.2.2 reads: GM vehicles may substitute the OEM panhard bar. The bar may be adjustable for length. The passenger side mounting point must remain OEM stock. The driver side mounting point may be lowered, but only to the point where the panhard bar is parallel to the axle at ride height.

There is never mention of allowing modification/substitution to the PHR upper brace, only to the PHR itself. My question is, does the brace fall under the same rule (is it all considered one piece), or is it considered a separate piece? Anything I'm missing?

[BryanL]

Nick-where are you finding this article? Is that suppossed to be a CMC legal car? What aboput that axle brace to the phb mount? And is that phb mount legal or the chain?

[NickV]

It's in the latest Grassroots Motorsports. Has an old 911 on the cover.

Car is stickered for CMC2.

I'm guessing the chain is there to keep the axle from drooping when the car is jacked up so the spring doesn't fall off it's seat.

[jdlingle]

I think they were running it in another class. The article said they got DQed from CMC2 at Nationals in 2010 but I dont remember what for.

[GlennCMC70]

That is an OEM upper PHR brace, but it has been modified and is not CMC legal.

The PHR mount shown is legal. Once you extend the mount downward, there is enough leverage to rip the whole mount off the diff. They have been known to do this in OEM form. I've had to reweld mine - and it isn't extended - as well as the one on the #3 car before Love bought it.

While on topic, the proper ride height for a 4th gen will pretty much put the PHR level while in the OEM holes. If we could lower both ends, that would be another issue all together.
The PHR in the above pic has the bar in the OEM hole.

[TJ Bain]

What about the smaller then stock, non-pigtail springs?

[GlennCMC70]

What about the smaller then stock, non-pigtail springs?

7.33.4 Springs of any rate, OD, ID and free length may be used. Springs must install in the OEM stock unmodified location using the original system of attachment unless noted elsewhere in these rules.

[AllZWay]

I sure don't see how welding a bar from the axle to the panhard bar mount should be legal. That is a big modification.

[Hood]

"The driver side mounting point may be lowered, but only to the point where the panhard bar is parallel to the axle at ride height."

When it specifically allowed, then it must be assumed that it needs to be done safely. Just as Glenn stated, the leverage on the mount is enough to fatigue it even in stock form. Lengthening it is only going to make it more prone to fail.

[BryanL]

I agree that the welded brace on the axle should be illegal.

So why allow the extended mount if it just creats a weaklink? Is the mount bolted or welded? If its welded then it's possible its not in the correct location. Seems easier just to not allow that mount.

Is the lower spring mount unmodified/stock? To me it looks like their is a taller insert and then a donut.

Would the chain also not limit the upward travel of the rear end?